Stark Countershafts, like those of many other makers, were available in a variety of forms from simple 3-speed units to more complex affairs where a multitude of speeds, in both forward and reverse - as well as stopping and starting - could be obtained instantly by flicking belts from one pulley to another. All Stark's early drive systems used flat belts - thankfully avoiding the wretchedly inefficient round leather rope or "gut" drive of many cheaper machines - and all included a control system that involved "fast-and-loose pulleys" where a belt, idling on a "loose" or "free" pulley which was free to rotate on its shaft, could be flicked across to a "fast" or "connected" pulley and transmit the power onwards, usually to a 3-step pulley, which drove a matching pulley on the lathe spindle.
Although the illustrations below show the countershaft which drove the lathe, it is worth remembering that this would represent only a small part of the drive system, especially on ones offering multiple speeds and reverse. If, for example, three fast-and-loose pulleys were employed to give high, low and reverse ranges - as on Countershaft No. 2 - then a matching arrangement, driven by overhead line shafting (or in later years an individual electric motor) had to be provided either above, below or behind it. No wonder that many of the largest advertisements in industrial towns of the Victorian era were for power transmissions systems of one sort or another - they could easily represent a substantial proportion of the cost of installing new machinery. When a basic Stark bench lathe cost $100, the No. 1 countershaft was priced at $12, the No. 2 at $18 and the No. 3 at $25 - and that was without the ancillary drive gear and line shafting required to bring power to them when the total cost would have risen beyond that of the lathe itself..
Later Stark lathes adopted underdrive stands and integrated drive systems with one lathe boasting not only a built-on motor but a completely enclosed variable-speed drive system..

"Counter No. 3" was the most complex and expensive of the early Stark countershaft units. The three fast-and-loose pulleys grouped together between the support arms were arranged to give a high speed, a low speed and a reverse setting. The unit would, of course, have required suitable ancillary drives - from overhead line shafting for example - to accomplish this.
A separate drive was also required to drive the long overhead drum - the purpose of which was to power, via a thin cord belt, a toolpost-mounted high-speed grinding or milling head; the length of the drum matched the between-centres' capacity of the lathe and allowed the driving cord to follow the lathe carriage as it slid up and down the bed.

"Counter No. 2" for wall or ceiling mounting - identical in function to the No. 3 unit, but without the ancillary overhead drive drum. 

"Counter No. 1" for wall or ceiling mounting - the cheapest and simplest countershaft in the Stark range. Two drive belts, each running in opposite directions, ran side by side on a central "loose" drum. By using a hand or foot control, connected by wires or rods to the countershaft belt-shifter arms, either belt could be moved outwards to run on a "fast" pulley - and so turn the 3-step headstock-drive pulley mounted on the end of the shaft.

Besides the normal range of wall and ceiling-mounted flat-belt drive countershaft units (of which several early versions can be seen here) by the early 1930s Stark were offering a neat, self-contained motor drive unit mounted on a substantial cast-iron frame and designed to fit beneath a bench-mounted lathe or miller. It was marketed not only for the company's own products, but could easily be set up to drive many other small machines which would otherwise have required a separate and cumbersome countershaft unit.
The unit, along similar lines of the Rivett "Oil Pan Stand" arrangement,  consisted of a supporting frame, motor and coupling, 3-speed gearbox and drum-type reversing switch. The speed-change lever could be operated whilst the drive was running and the gearbox - with non-metallic gears engaging with hardened steel gears running hardened shaft - ran in an oil bath. The box contained three shafts, all supported on adjustable Timken roller-bearings.
Unfortunately, instead of being arranged to mount longitudinally, the unit was designed to be positioned transversely which made the bench unacceptably deep.
In 1936 a variable-speed drive system was patented by Stark and built into the underside and rear of a bench precision lathe--the design enabling the machine to be self-contained and ready for immediate use. The design was by a Mr. T.Potter, an employee, and assigned to the company under No. 20,797

The complete under-bench drive unit showing the supporting frame, motor and coupling, 3-speed gearbox and drum-type reversing switch.

With the model number often cast into the bed identification of many Stark lathes is foolproof.
The elliptical bed foot was a distinctive Stark "trade mark".

Left: a double row of spindle-indexing holes drilled into the flange surrounding the largest headstock pulley on a Stark No. 31/2 lathe.
At the rear of the headstock front bearing is a lever that engages a pin in one of four holes drilled into the front face of the smallest pulley.